Substrates for thin-film transistors, which may sometimes be abbreviated to “TFT”, used for devices such as liquid crystals, are ordinarily made of inorganic materials such as glass. The production of a display with a non-plane screen such as a curved one requires a flexible TFT substrate. In order to answer this requirement, researchers have considered making TFT substrates with flexible resin. However, resin is apt to be inferior in barrier properties against gases such as moisture and oxygen gas to inorganic materials such as glass. Then, to provide a substrate with flexibility and gas-barrier properties made by layering a resin film on a glass film has been considered.
A method of producing a flexible TFT substrate by forming a TFT substrate on a glass film that has been layered on a temporary substrate and transferring the glass film to a resin film is known. Concerning this method, the employment of a photosetting or thermosetting adhesive to stick the glass film to the resin film in order to make a laminate substrate is reported. However, when a thermosetting adhesive is used, the shrinkage on curing is large while the glass film is being stuck to the resin film, which often causes problems such as deformation of the substrate and breaking of the wires. On the other hand, when a photosetting adhesive is used, the TFT substrate is irradiated with intense light beams during the curing, which may cause deterioration in the transistors on the TFT and change in their electrical characteristics.
In these situations, the sticking with a thermoplastic resin has been studied. Patent Document 1 teaches that a particular thermoplastic polymer with ring structures is useful as an adhesive for semiconductor materials, and it also discloses a method of sticking with it under a heated and pressurized condition. Patent Document 2 proposes an adhesive including a cycloolefin resin and a solvent and also recommends the sticking under pressure.    Patent Document 1: WO 99/01519 A1    Patent Document 2: JP 3-95286 A